Telephone repeater system.



PATENTED AUG. 27, 1907.

NP G. WARTH.

TELEPHONE REPEATER SYSTEM.

APPLICATION FILED JAN. 25, 1907 FULL NATHANEEL @WARTH PATENTED AUG. 27,1907. N, WAR TELEPHONE BEEPEATEE SYSTEM.

APPLIGATION FILED 5103.25, 1907..

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A2 xc amewtoz MWMATHANIEL G.WARTH UNITED sTArns PATENT, OFFICE.

NATHANIEL G. WARTH, O F COLUMBUS, OHIO.

TELEPHONE REPEATER SYSTEM.

No. sos'. -n a.

This invention relates to improvements in telephone current repeaters orrelay re-inforcers and systems for their operation ofthe generalcharacter illustrated in the United States patents to Herbert E.Shreeve,.as

follows: Nos. 791,655 and 791,656 dated June 6, 1905,

and 835,037 dated November 6, 1906, and isa modified form of andanalogous in its major principles to the repeater apparatus and systemdiscolsed in my patent of the United StateaNo. 845,282, dated February26,

' repeater for the purpose of preventing the local self-v action lrnownaslfhowling, or singing; efiecting The present invention like thatcovered by my patent above reierred toinvolves conditions of operationand" accomplishes beneficial results in providing a constant balance forthe repeater apparatus, regardless of the staieof balance of the linecircuits connected with the the elimination of auxiliary coils andcondensers, de-

rived or balancing circuits, drc., which interfere with transmission byproducing distorting reactive currents and cause an unnecessarydissipation of the current.

The important feature of my present improvement is thearrangement andlocation of the line repeating induction coil windings in the sectiohsoi the line cir' cuit, whereby direct through or original transmissionfrom the transmitting station is reduced to a minimum.

This condition is also largely contributed to by my use of a very lowresistance 3 bridge betweemthc two sides of the line, in which norepeater coils or windings are included, and which contains no repeaterapparatus, but when the line circuit is also used for compositedservice, which combination is with this repeater syste'ih especiallycontemplated, a condenser may be included in the bridge. Thisarrangement, together with my combination of divided or bridged localcircuits, effects a condition of minimum direct transmission across therepeater station of tlie system, thus insuring singlencss of action andgiving a clear reproduction and amplified re-tmnsmission into thereceiving end orsectionof the two sectionsohline circuit. This system,it will be noted, is also similar to that embi-aced in my patentmentioned above, in that the ire-transmission being divided iseffectedsimultaneously in both directions or line circuit sections.

'Another important object of the present invention is to secure anequalized transmission toward each terminalstntion, and particularly toprevent a line section oi 'low resistance from taking a disproportionateamount in the retransmitted current, each line section thus re-Specification of Letters Patent, Application filed canary 25 1907.Serial No. 354,089-

Patented Aug. 27, 1907.

separately and equally in -each line or circuit section, 6=

and being confined therein by the low resistance bridge. The resistanceof the associated circuit and its coils offers an additional barrier tooverflow or direct transmission from line section to line section, andthese conditions in association. with the dividedlocal circuits, 7;

to be described hereafter, practically prevents such action and alsothat of the initial or originating currents being conductivelytransmitted into the associated section of line circuit past therepeater. These conditions produce the hereinbefore mentioned singlcnessof ac 7i; tion or effect upon the repeater-receiver, and effectuallyavoid echo like reaction currents,and distortions of the currents by therepeater apparatus.

While. the invention chiefly. consists in the above features it furtherconsists in the provision of a 8O culisrly'arranged composite toroidalform of repeating induction and retardation coil, whereby and whereinreactnnce orret a-rding effects are minimized for the telephonic orvoice currents, and also for any direct or through transmission ofcomposited or superposed ofi currents applied to the same line wires.For the latter class of service the invention also consism in auxiliaryapparatus an circuit arrangements associated with the composite coilwhereby phantom circuit' or additional superposed currents, or service,

is especially provided for and enables the phantomed telephone (orsimplex) transmission to pass the repeater station without interferenceand with no interference 5 to the other simultaneous transmissions. Thisspecial induction coil is the common or dualmeans for the operativeassociation of the repeater apparatus with the line circuit or circuitsections for both the receiving and re transmitting currents. Thesecondary windings of the coil are preferably divided into four helices,

J'LWO of which are symmetrically disposed on quarter 10(':

sections, on each half of the ring core, each pair of windings beingdifferentially but conductively connectcd together in the through linecircuit serially,

. one winding or helix on each side of the bridge, on each side of theline. These windings are the secondary or main line windings oi thecoil, and are traversed-by the 1 elephonig: or voice currents, thetelephonicsignaling or ringing currents, and, when the circuit isutilized for superposed or composited sen-ice, also for thoseii'urrents, whether they be direct, pulsating 0r alter 11G uating incharactr. r i I When ringing currents, composited telegraphic, or

signaling currents, are transmitted, either alone or simultaneously withthe telephonic currents, the repeater apparatus being in circuit, isordinarily subjected to more or less violent and undesirableaction. Thisaction. or effect in my arrangement is practically overcome, or ratheris avoided by the differential windings referred to above, and whichwill hereinafter hemore particularly explained in connection with otherfeatures of the arrangement of the coil and its cohnections.

A great desideratuni in connection with extending the range oitelephonic transn'iissien by means of a repeater, is the flexible use ofthe apparatus by the ordinary switching operators. whereby with arepeater apparatus installed in a cord circuit", operators mayarbitrarily or without any fine discriminationas to the resistances orother peculiar conditions, connect two circuits togethcr. as rcadily isordinarily the operation of connecting two lines; or with no morejudgment or effort on their part than is usual when a connection isestablished by including an ordinary repeating coil in a throughcircuit. The equal division and predetermining of the division or(tree-- tion of the re-transinitting currents in the two circuitsections, together with the condition of constantly nmintained balanceof the repeater receiving element against local action, renders myrepeater arrangement highly eliicicnt and peculiarly adaptable to suchgeneral switching service.

For economic reasons "long distance circuits are frequently used forcoirposite service, that is, telephoning. tclcgraphing, signaling, do,sinultancously over the same wires. Usually the telephone circuit isoperate-(l as a metallic circuit, and the other or superposcd circuitsas "grounded or earth-completed circuits. To adapt my repeater systemand apparatus.

n u I with condensers inserted at the middle of-the secondary to suchcombined or composited service, and to do so with a minimum of mutualinterference, and as a pro ict'iion to the repeater apparatus proper, itis desirable to affect the clliciency of transmission of the superposedcurrents as little as possible, and to shield the repeater apparatusfrom action by the non-telephonic currents. As. the repeating inductioncoil secondary windings are included in the line circuits in thisinstance, the superposed currents are transmitted there through. Suchcurrents being usually of low frequency and great volume compared withtelephonic currents, have time to quite thoroughly magnetize a core ofthe character used in such a coil. Such a core effect would caus thecoil to seriously retard tht superposed currents, especially since theymust traverse two windings, one on either side of the bridge. Such aneffect would tor would not, according to the current frequency also setup or croatean undesirable action upon the repeaterreceiver-transmitter. Both undesirable ef ects 1 practically overcome byconnecting the two windings non-inductively, or differentially, to thethrough superposed currents and without ai'hctin; the telephoniccurrents because their circuit is completed through the bridge andpasses through the windings in their line circuit section side of thebridge onlytas will be more particularly explained. Certain other advirntages also accrue in this respect by utilizing the various windingsof the composite coil to render the non-telephonic currents harmless tothe repeater apparatus. Ringing currents, as with the telephoniccuirents, are usually applied to the metallic circuit, and their violentaction would operate the repeater injuriously. This effect can bepractically avoided by connecting the two telephonic .windings of thecoil, that is, one winding in each conductor on the same side of thebridge, non-inductively or differentially. Low frequency ringingcurrents in this in: stance'would produce a neutral field or core effectand not. set up a strong induced current to violently affect thereceiver element of the repeater in its local circuit,

because the local windings are in neutral inductive relation to thesecondary or telephonic windings. higher frequency telephonic currentshowever, due to the magnetic reluctance of the core, produce efficientconverting action by reason of the windings creating The or elementaryform and developments of that form to l the preferred form, suchdrawings being so made to facilitate an understanding of the physicaland superposed circuitsand the composite coil connections.

Figure 1 is a diagram illustrating a compound circuit for a telephonerepeater composed of two line circuit sections conductively ending at arepeater station in a repeating induction coil, with a winding each uponthe same core and also representing a local or primary circuit with itswinding upon the core; Fig. 2 is a diagram illustrating a similarcompound circuit, but equipped windings of the repeating induction coil,conductively or physically separating the two sides of each line circuitsection, and with inductance or retardation coils physically connectingthe circuit sections on each side, thus providing for superposed director through transmission on each side of the compound circuit; Fig. 3 isa diagram illustrating such a compound circuit provided with a compositeretardation and repeating induction coil and a condenser which togetherfulfil, in a simplified way, all the functions of the apparatus andarrangement shown in Fig. 2 for both the telephohic repeater andcomposite services; Fig. 4 is a diagram representing the invention, partcularly as to the telephonic or repeater conditions, illustrating mycombination of divided repeater circuits, embracing the main or compoundthrough circuits with the low resistance bridge; the repeater-receivercircuit in which the receiver is operated inductively by the initialtransmission from the terminal telephones, and is in a state ofmaintained balance against, and inert to, its jown repeater-transmittercurrents; and the split or divided repeater-transmitter circuit, havingthe battery or current supply, and'the repeater-transmitter elementincluded in the dividing conductor of the circuit; Fig. 5 is adiagrammatic representation of a complete com pound repeater circuitarranged for composite service, and having asc iciated therewith thecomposite coil,

which fo clearneds is illustrated with each of the plural windings onseparated sections of the .ring

core, the primary and the tertiary windings being the main line circuitsof the system with the associated apparatus therefor, embraunia flexiblecord-circuit and, in addition to the telepli nic, repeater and com.-posite circuits, an arrangementlior a phantom circuit, or a specialsimplex circuit, alsoinductance and inductive shunts around the epeaterfor particu lar operating and service purposes.

In Fig. 1, as in all the views, L and L signify two sections of ametallic telephone circuit, or two metallic circuits, which in each caseare assumed to be inductively joined with a telephone-repeaterapparatus. I

In Figs. 1, 2 and 3 the coil windings 0, G &c., represent the secondarywindings for" the repeater and Po the primary windings. r W and Wsignify one side of the through circuit, and W and W the other side ofthe circuit; W and W and W" and W, corresponding to the L and L sectionsrespectively, in all the views, offthe composite circuit. OX signifiesthe core of the repeating induction coil and is shown in dotted outlinein Figs. 1, 2 and 3.

My invention, as the views throughout show, contemplates the division ofthe through compound circuit into two telephonic circuit sections, eachsection being complete and terminating at the repeater station,

wherever it happens to be connected or included in said through circuitby means of its repeating induction coil winding or windings, and thistermination comprehends the connection between the windings when theyare separated by a short conductor, which may include a condenser, :asis shown in Fig. 2.

In Fig. 2, Dreprcsents the short conductors and J and J 2 condensers insame, connecting the inner terminals of the coils 0, C and coils G 0,respectively. To adapt a circuit, so physically separated, to direct orthrough transmission across the repeater station, especially' for formsof direct current telegraphic service, the circuit sections L, L areconnected together around the repeater apparatus or station, by the useof conductors A, A, in which suitable inductance or retardation coils F,F are included, as shown in Fig. 2. These coils F, F serveto preservetheseparation of the circuit sections telephonically yet permit thepassage of direct or low frequency, &c., currents.

The condensers J, J are required to separate the two sides of thecircuit when the composite service, by which is meant thesuperposedcurrents, is separately operated on the two wires or sides of thecircuit, as is illustrated in Figa, 51 and 6. Suchcurrents, as is wellknown, are practically stopped by a condenser,

' but such condenser will permit the passage of high frequency, &c.,currents. To simplify the apparatus for use in such combined service,and also for special adaptation to the fleriblc handling and use of thecirunits, as will he set fault in further description of Fig.

6, I prefcrto use the.a. rrangement shown in Fig. 3;.

In Fig. 3 the repeating induction coil has the windings O, C and (J C,pn eachhsidc respectively of the circuit, connected together to formtherethrough a conductive through circuit, the windings so connected.

being differentially associated and serving'also as inductance coils inlieu of the coils F, F which arehere omitted. The short conductors D ofFig. 2 are, by this method of connecting the windings together, replaced by the short connection or bridge H, in which a single condenserJ may be utilized to advantagein lieu of the two separatecondeusersoifsaid view. Thus arranged the several circuits areoplatively as distinct" as when physically so. I

The coils in l, 2, and 3have cores of the usualv straight bai; or opencircuit form, and while such coils are not ordinarily as effective ascoils having the ring 7 or closed circuit form or" core, the bar oropenform of core has, when provided with the separated sectional windingshown and, described, the same functions as my special toroidal type ofcoil, which is divided into distinct plural electro-magnetir;sectionsfor independent sectional core effe cis. p

In Fig. 4, the two circuit sections L, L together with the terminal,stations S, SE and the repeater equipment at the intermediate station,comprise a complete telephonic system for long'distance communicationrequiring repeater service. In this view the coil windings are arrangedinrcooperative relation and straight series connection; i

The flow of the currents are conventionally shown as follows: primarycurrents by short'solid arrows;

initial or repeating line currents by longsolid arrows;

and reproduced or repeated line currents by broken arrows. An initialtransforming line current'being set up at the telephone S would at theintermediate or repeater station, traverse the repeating induction coilwindings C 0, and the low resistance connection or bridge H, and wouldinduce current (also indicated by long solid arrows) by means of thetertiary windings 'l T, in the half G of the repeater receiver ('l)circuit, 'thus energizing said receiver. Neither the initial currentsfrom the line, nor the currents induced therefrom, in either. theprimary or the tertiary windings or circuits, penetrate their respectiveassociated like windings or circuits, by reason of the low resistancedividing cross-conductors 0r bridges H, P and TX, respectively. Thereceiver T winding, of the repeater apparatus It is connected into thebridge conductor TX, and the transmitter M of the repeater apparatus R,together with the local batteryB, are connected into the bridgeconductor P. Thc'energizing of the receiver actuate-s the transmitter M,the two elements being in repeater relation to cornprise the repeaterapparatus It, which varies correspondingly the resistances of thedivided primary or local circuits and enables battery B to set upreproloo duced currents in facsimile, to flow through the four I circuitG, G.

would cause a current flow in the secondary windings of the inductioncoil SC upward (in the diagram), thence to the left in the lineconductor W thence through'winding C of the repeating induction coil,thence to thejunction with the bridge conductor H, thrdugh the bridge tothe junction with the line conductor W thence to the right to andthrough winding C of the repeating induction coil, thence to the pointof starting at terminal telephone S The pass ing of the current throughthe windings C 0" would induce a corresponding current to flowoppositely (see the inner long solid arrows) in the associated tertiarywindings 'l T, and that circuit as follows: Beginning at winding T atthe top, flowing to the right thence downward, in the G2 circuit, thenceto the left toand through winding T at the bottom to the junction withbridge conductor TX, through the bridge and receiver T therein, to thetop junctiorr'of the bridge with the G circuit and to the right to andthrough winding T? the startirig point. The receiver T being thusenergized and actuating'the transmitter M would set up a primaryreproducing current flow as follows: Starting from the positive pole ofbattery B, in the bridgeconductor P upward to and through thetransmitter M thence upward to the junction of the bridge with the B",B" sides of the primary circuit. At said junction the current divides,flowing to the right through the B circuit to and through the primarywinding P associated with line windings C ll'lGllCO around to andthrough the winding P asse ciatcd with line winding 0 thence to thejunction with the bridge P and thence to the negative pole of thebattery. The other portion of the current flows to the left from thedividing point through the B circuit .to and through the primary windingP associated with line winding C, thence around to and through thewinding P" associated with line winding C thence to the junction withbridge P. where it unites with the other current. The flow of thisbattery current through the primary windings induces a facsimile currentin all the windings associated, and this induced current flows in theopposite direction to the inducing current (soothe directions of thebroken and short solid arrows respectively). For the line circuits, thebroken arrows are shown in the reciving or L section only. Thisparticular secondary current is confined to that section of the circuit,the flow beingclearly shown by the broken arrows, as follows: Startingat winding C flowing? to the right to and through the bridge H thence tothe left through coil thence through line conductor W to the terminaltelephone at statioir S thence returning through line conductor W to andthrough winding Oto the starting point. A like flow occurs in theassociated circuit section If, which under the circumstances isdissipated energy. Simultaneous and analogous inductive effects areproduced in the divided tertiary The same broken arrows at the four '1windings represent the induced current in this circuit.

It will be observed that the primary windings P, P in the B side of theprimary circuit'are so connected that-the battery current flows to theleft, as is also the direction of its flow in windings 1?,1", on the Bside of the circuit, This arrangement, without changing the straightconnections for the associated windings the L side of the repeater,produces a flow of the'iri} duced current in the tertiary circuits inthe same direction, (see the broken arrows directed to the right at thetop) down at the right and to the left at the bottom, thence up at theleft and down throngh tho bridge TX and receiver T on the left side ofthe bridge conductor, thence up through the bridge and receiver on theleft side of the bridge conductor. As the two sides of the circuit arebalanced and the induced currents therein are also balanced, a conditionof no difference of potential through the bridge is produced, resultingin no actual flowoi current in the bridge and the receiver '1, whichneutral state, to the re-transmitted currents, leaves the receiverunenergized and silent, and the transmitter inert. It should beunderstood that the reciprocal of these current flows and effects occurswith each change in the direction of transmission or use of the line.

The arrangement of practical division of the main,

tertiary and primary circuits effectually prevents interfering reactioncurrents and effects, which in other repeater systems are present andcause distortion of the reproduced currents by out-of-phase or echo-likeoverflow or reactancc currents, due to direct transmission into thesection of the circuit then receiving, hence each circuit section, mainand local, and the apparatus as I describe it operates as independentlyas would be the case were the circuit sections physically separated,(which is also within the scope of my invention) and the resultingtransmission is as directly induced into each line circuit as is theinitially produced transmission at the terminal telephones.

Reaction currents and their interfering effects, as referred to herein,are particularly explained inflmy patent above referred to, as also aretheconditions Fig. 5 is adapted particularly to an explanation of thecomposite repeating induction and reactance coil, and to the compositeservice conditions heretofore mentioned. This induction and reactancecoil is-preferably of toroidal form with the core OX composed of abundle of No, 22 annealed soft iron wires, as is now which crcatetheself-action effects producing howlingp usual with good forms oirepeating and induction coils,

and the coil should be closely covered with a soft iron shcll or casingto concentrate the stray field and for protcction against injury. Thewindings can ,be of 2 any gage of wire and number of convolutionsadapted to the desired use. The primary helices P should be wound nextthe core, each of the four sections equally positionedon quarterdivisions of the common core. For usual service conditions the "windingfor each section should consist of about one hundred and fifty turns ofN o. 19 gage double cotton-covered copper wire. The twoputr helices oneach section may be so arranged that the tertiary windings are eitheroutside or between the primary and secondary helices, or they may bealternately positioned if the number '0': turns around the core arecompensated. Each helix should consist of about twelve hundred turns-ofNo. 27 wire, and the resistance through two windings inseries should notexceed one hundred and'fifty ohms. In said view the primary helicesare-the inner or core windings, the secondary-windings C, G, G" and 0are in the centerand the tertiary windings'are outside.

- 7 these small magnetic fields are made more intense and I efficientfor this condition by the provision of theiron I local circuits. Acrossthe diameter of the coil, at right angles to the before mentioneddirection, the secondary windings on each side are also differentiallyconnected, C with C and C with C, which provides for a minimum ofinductive action to the repeater local circuits, and consequentvidleric'e to the apparatus, from strong currents circulating in eitherline circuit section, as previously explained. The four tertiarywindings T correspond to thefour secondary sections, and as suggestedabove can therewith be interchangeably alternated or associated. Thewindings, however,- can under other circumstances be of larger wire, astheir function isto operate the receiver T, which is in a low resistancelocal circuit. The receiver may also then be wound with larger wire withsome advantage. The.

application of the tertiary windings to the receiver T 'circuits, issuch, on each side of the bridge, theta telephonic-impulse :in itssecondary windings irom a line circuit section, will induce acooperative flow oi current in the two windings ('l"), the current beingshunted through the bridge TX and receiver T by reason of the lowresistance of the bridge. The local fields created in the coil bythetelephonic currents having been explained, it remains to be statedthat shell referred to, which concentrates the stray field in eachsection by providing a short return circuit. This is true particularlywith reference to the differential conditions. The four primary windingsare also differentially connected on each side of the bridge, in thisinstance, bridge P, and the inductive "actions are similar owing to therapid variation of current which the transmitter creates" in the batterycircuitsB B and correspondingly energizing the windings.

The several local conditions and effects are similar to those describediii-connection with Fig. 4. While the differential connections arepreferred, thrbughout the several ,c .uits, yet it is practicable tovary them without departing from the essential features of theinvention, The primary windings may be connected cooperativelythroughout or cooperatively on one side and differentially on the other,and-the tertiary windings maybe similarly vgried. With the receivingele- I mont. T of the repeater apparatus R, I prefer toemploythopermanent mag'netU for establishing its residual or initialmagnetic field forsensitization, In this I {.iziiw the'superposedservice is adirect cu'rrent telegraph circuit on each side of thethrough line circuit, which arrangement is usually termed composite asdistinguished from simplex and phantom. The conductive separation of thecircuit sides is effected at the repeater station by condenser J; at theterminal station S by condensers J, J; and at the terminal station 8' bycondensers J, J, the telephonic circuit sections being, in thisinstance, the some as in Fig; 4,

with the exception of these condensers. The tel graphic circuits havecornmouground connections in E and E", and common sources ofonergyin'batteries TB and T13 The lower circuit in this view is definedas follows: From ground E to and through bat tery 'll-l, thence tojunction Y of the battery tap, thence to instrument h, line wire W,coils C, 0, line wire W, instrument K battery tap Y", T13 ground 15 andearth return. The upper circuit is similarly defined between Y and Y byway of the earth, thence from Y to instrument K, through line wire W,coils C, C, line wire W iustrumentnKi, and

thence to Y*.-

In Fig. 6 the repeater local circuits and apparatus are eliminated, asthe scheme of this diagram has to do particularly with the conditions ofcircuit and appamtus for connecting the repeater secondary circuit intothe line circuits and with the operation of the 8 superposed circuitspast the repeater. The terminals of the two telegraphic circuits areomitted to avoid detail. 7 The flexible operation of the repeater bymeans of cord circuits is illustrated in this view, the outer terminalsof the four secondary windings, G, C, 8 C, 6, being connected by cordconductors, Q, Q"), Q. Q, to plugs V, V, V", V, thence to thc line c0nductors W, W W W, by means of the jacks 0, O 0", O, allrespectively. Inpractice the cords, plugs and jacks would be of the usual combined formfor metallic irc'uits and similarly associated on each side therepeater, and with other equipment details well understood by thoseskilled in the art andv unneces sary to illustrate. For economy inapparatus and simplicity of operation it is preferred that the sec- 9ondary coils and the cord circuit equipment shown in the view shall bewithdrawn from the through line circuit, for composite service use, butwhen, the re pcater is not required for that same through circuit, Iprovide the auxiliary conductors A, A, and A, A, on each side oftheeircuit. containing proper inductance coils F, F? By this arrangementthe slow acting superposed currents may traverse both the repeatinginduction coil windings and the auxiliary coils on each side ofthocircuit, thus securiug'a'more 1 efficient circuit, and when sensedsuch division of the superposed currents offers additional safety to therepeater apparatus. Should the secondary windings be required to operatecooperatively, or should it be desirable to prevent heating of theapparatus from the 1 strong superposed currents, such through currentsmay be caused to. be transmitted through the auxiliary conductors byinserting condensers in the cord circuits. The foregoing provisions ofthe cord circuit, and auxiliary apparatus, permits circuits to be ,used1 for the ordinary long distance telephone service when not required forthrough or repeater service, and also permits various similar repeaterconnections to be established between circuits at a station havingrepeater battery equipment. In practice the line circuits may beterminated at a test board where the composite appar' tus is lpcated andconnections are usually made and the lines then extended to theswitchboard for the regulart'elephonic operation. The superposedtelegraphic currents in this instance have their circuits, 12 b asexplained in connection with Fig. 5,-excepting that at the repeaterstation they are passed through the secondary windings i the compositecoil, and through the auxiliary conductorsi- ,At the terminal stations Sand S, the receivers N,

N are connected at the middle of their windings with conductors X0 andX0 respectively, leading to apparatus X and X respectively, which, asherein stated, may be either telephonic or telegraphic apparatusoperated by high frequency currents. If the apparatus used istelephonic, the connections leading out on the opposite side to the deadends XE and XE respectively, would connect with another'and paralleltelephonic circuit, while if the apparatus is telegraphic in characterthe connections may be with another circuit, or with the earth, orotherwise; sufiicc it to state that sucha superposed circuit is termed aphan torn circuit if telephonic or a simplex circuit if telegraphic incharacter. If a current impulse is set up at instrument X assuming it tohave a positive flow through the system as shown to its correspondingstation X, it will pass through the conductor X0 to the middle Iconnection with receiver N, where it dividesand flows differentiallythrough the split windings of said receiver, and thence each half of thecurrent will pass along its respective circuit as follows: The halfpassing upward through condenser J- will follow conductor W I to itsjunction with the auxiliary conductor 1 thence along that conductorpassing through condenser .l in circuit in conductor I, to the junctionof conductor Itwith line conductor W thence to and through condenser J 5and the lower winding of receiver N, thence through conductor X0 andinstrument X to XE, and finally completing its circuit back to X by anypath that may 'he provided for it as indicated above. The other half ofthe current will find a likepath from receiver N" through condenser .l",line conductor W; auxiliary conductor I and its condenser 1 to andthrough line-conductor W, and condenser 1 thence telephone S or 8*.

posite apparatus.

differentially to the first half through receiver N to and uniting againwith the first half. Such currents will not affcctthe telegraphic ortelephonic apparatus, as already sufiiciently described herein,excepting as IfollowsrThe telegraphic apparatus first described is toosluggishin action to respond to the character of currents applied tothis additional circuit, and such currents are unable to penetrate theretardation coils usually associated with the telegraphic apparatus (notsion into the receiving line circuit from either terminal; As anadditional precaution against such action condenser .l in the bridgeshould be of ample clcctro-static capacity.

What I claim and desire to secure by Letters Patent 1. In a telephonesystem for the reproduction with increased power of the initiallytransmitted currents from terminal telephones, the combination of atelephone re pester receiyer-transmitter, a main circuit, and 'a bridgeat the repeater station'dividing the main circuit into two circuits ortwo associated repeater line sections; u repeatingindnction coil at therepeater station having sectlonally divided plural secondary and localwindings, and

semis having the secondary winding divided between the two sections ofthe main circuit with said bridge connected to each side of the maincircuit between said divisions of the winding; 21 local circuitembracing, a part of said plural local windings for therepeater-receiver and a local circuit also embracing a part of saidplural local windings for the repeatentransmitter, each said localcircuit having a bridge dividing its plural windings, said pluralwindings being wound to correspond with the said secondary windings andadapted to produce substantially equal effects through said localcircuit bridges, and all thewindings in each division of said coil beingmutually inductive: the repeater-receiver and the repeater-transmitterbeing in circuit in the bridges of their respective local circuits, anda battery also in the local circuit containing the repeater-transmitter;

said repeater-apparatus being sensitive to the inducing initial linecurrents from each line section but insensitive and inert to itsreproduced currents in the line sections, and to prevent local selfaction.

2. In a telephone repeater system, the combination of 11 repeaterapparatus, a main telephonic circuit, a main bridge dividing saidcircuit, a repeating induction coil having its secondary in saidcircuit, windings of snid secondary being included in said circuit oneach side of said bridge, local circuits for the receiver andtransmitter of said repeater appnratusylocal bridges dividing said localcircuits, the divisions thereof being electrically bulanced, and eachcontaining local windings of the said 'coil associated with respectivesecondary windings thereof,

one of said local bridges containing the repeater-receiver and the otherlocal bridge containing the repeater-transmitter and ubattery, means forrendering the receivertransrnitter operative inductively to the receivedcurrents, but inoperative to the local and reproduced currents.

3. In a telephone repeater system, the combination of 'a repeaterapparatus consisting of a receiver and a transdnltter ln repeuterrelation, a line circuit consisting of two circuit sections eachinductively associated with said repeater receiver and transmitter,local circuits for the local self-action and against unbalanced linecircuit e f:

fects.

4. The combination. in a telephone repeater system, oi.

a receiver-and transmitter associated in repeater relation,

a repeating induction coil having plural windings both secondary andlocal. a transmittingline having n section on each side of the repeaterapparatus and inductively associated with the receiver-trunsmitterthrough said coil. the repeater-receiver being connected in circuit withthe local .windings in a constantly maintained balanced relation wherebyit is rendered insensitive to its own buttery currents but sensitive tothe inducing currents from the line circuits and their associatedsecondary windings. the said secondary windings of the coil beingdivided between the line circuit sections, ihe'divisions in each cii=cult section being operative therewith individually io insure singlcncssof transmission effects and properdivision of current.

5. In :1 reciprocal telephone repeater system, the com bination of ainaimansmitting cil'cuii' divided at u repeater station into t o linecircuit sections, terminal icle-' phones associated therewith tooriginate currents for reproduction. and a repeater apparatus comprisingan electromagnetic telephone receiver and .a variable resistancetransmitter associated in repeater relation to receive the telephoniccurrents from one of the circuit sections and to transmit facsimilecurrents of greater power to the associated circuit section and theterminal telephone apparatus therein, a repeating induction cell havingplural secondary and local windings, said secondary windings being inthe line circuits and divided between and appon i'ioned to the sectionsthereof, the repenter-receiver and transmitter both being connectedln'circuit with local windings of said induction coil and inductively mlclated thereby with the line sections to furnish the reproduced currentsto each of said circuit sections simultaneously.

6. In a telephone repeater systemfthe combination of a' repeaterreceiver-transmltter, two line circuits, at repeat ing induction collconnected in the line and inductively joining the line circuits withboth the repeater-receiver and transmitter, said repeating inductioncol] having a plurality of secondary windings divided between the twoline circuits, and a plurality of local windings divided between therepeater-rece'iver and transmitter whereby they are in localrelationship to the l jnecireuits, and both are in common inductiverelationship with the secondary windings of said coil in the linecircuits, and whereby each line circuit is supplied with the reproducedcurrents from the repea er by its individual secondary windings, and therepeater; :cciver is suppllethwith individual induced currents from eacline circuit.

7. In a telephone repeater system, the combination of av main telephonecircuitcomprising two line circuit secreceiver and transmitter eachbeing in circuit with sep araic local windings of the repeatinginduction coll, the

secondary windings being associated with ouch other and with the line asfollows: a winding-for each circuit sec" lion on cach'side of the line,the windings being connected to each line coru'tuctor iiulividually ateach side, the wind tags on each sidebavlng'their other terminalsconnected and the connected terminals coupled by a low resistanceconductor, thus providing individual secondary windings for each linecircuit section.

8. lo a telephone system for reproducing the initial currents withincreased'powor for extending the distance of transmission directly, :1through compound line circuit comprising two telephone line circuitsterminating in a repeating apparatus at an intermediate repeaterstation, a repeating telephone consisting oi a receiver and atrailsmittcr associated in repeater relation and a repeating inductioncoil having plural secondary and plural local windings, a bridge of lowresistance at: the repeater station connecting the two through linecircuits :fnd terminating the line circuits; the secondary windings ofsaid repeating induction coil being divided and apportioned to each linecircuit.- bul said windings collectively being in operative relationwith both the receiver and transmitter and receiving from andtransmitting to the line circuits the telephonic impulses therepeater-receiver and transmitter being in circuit with the localwindings of said coil and adapted to be actuated only by the currents induced from each line circuit.

il. in a telephone repeater system, the combination oi a main linecircuit, a repeater, said main line circuit being divided into twocircuit sections at the repeater, local circuits tor the repeaterreceiver and lransmiii'er a rcpealing induction coil having secolularyand local wimi iugs. lilo second; v windings being a mortioucd'to twoline circuit sections and the local windings apportioned to the localcircuits, both said receiver and transmitter being in direct inductiverelation to the secondary windings of said coil whereby said secondarywindings serve in common for the inward and outward currents ol therepeater rc wielv and transmitter respectively, the secondary windingsat each side being connected to their respective line conductors, andsaid windings on each side having their other terminals connected, andsuch connected terminals being coupled by a. condenser, forming a lowresistance path for the teieplu'uiic currents to traverse between themain line circuit conductors.

bination of a. 11min telephone-circuiit, a ln'lligeconnection betweenthe conductors thereof, a repeater apparatus comprising a receivingmagnet and a variable resistance transmitter actuated thereby. arepeating induction coil interposed between said maincircuit and the said repeater apparatus, said repeating induction coil having a secondary5 winding composed of four helices, each helix being wound over aseparate section of a magnetic core, and'conneci'ed in the maintelephone circuit so that two divisions of the wlnding w ill be on eachside of said bridge connection. and eight local helices divided into twogroups otfonr substan r tially equaldivisions and wound to correspond tothesaid secondary divisions, each section of ,the core thus having threehelices; four local helices, one for each section of said corefa batteryand transmitter circuit containing a bridge two helices beingeounected'togcther on each side corresponding to the two secondaryhelices on each Side of said first named bridge, and eachpair connectedtogether and to the last named bridge conductor by their remainingterminals, so that said bridge conductor, its battery, and

mary circuit to correspond to the divisions of the secondary circuit; athird bridge conductor containing said receiving magnet with which thefour remaining local helices are similarly connected.

1]" In a telephone repeater system, a laminated iron ring core repeatinginduction and retardation coil, having four'electromagnetic sections,individual secondary and primary mutually inductive windings for eachsection} two secondary windings on each hall at the core across one sionwith two terminals for connection to the',line, a.

bridge connected on each sidef to the Joined terminals of the two saidhalves, said bridge connection being made to form two halves of the coilacross a diauieteralt right angles to the aforesaid diameter. of thecore, the latter halves being composed of one coiloteacb of the formerhalves,

and tog ther constituting four overlapping secondary'ci r cults. adptedto be variously connected for inductive and non-inductive effects forsingle and simultaneous service. 12. In a telephone repeater system, atelephone repeater apparatus, comprising a repeater receiver andtransmitter,

two main telephone circuits or circuit sections, a cord circuit joiningthem, saidiordectr'u it containing a repeating induction coil, dividedsecondary and local windings in each elrcult section when the cordcircuit is in use, the

repeater receiver and transmitter being directly connected in circuitwith the local windings of said repeating induction coil, andinductively associated with the secondary windings of said cell, andwith nib main telephone circuits".

13. In a telephone repeater system comprising two sections oftransmitting line. a Repeater apparatus and instrn=- ment circuits localto said llncnnd at an intermediate e a tion thereon, the combination ofmeans within said local ctrreceiver. said means when operating as abalance being independent of the line to prevent the creation in thereceiver of selfatction effects tending to disturb-the transmission anddistort the-form ot the'orlginatlng currents,

initial telephonic currents in said main circuit from being transmitteddirectly beyond the repeater; a repeater apparntus'comprising a receiverand a transmitter in repeater relation, and a repeating induction coil,the secondary windings of which are in the'niain circuit sud the local'windings of which are in circuit with the said repeater apparatus.

.15. In a telephone repeater system, the combination of a main circuitand twomlocal circuits, each of which is divided to form separatecircuits, a repeating induction 160 thevariable resistance transmitter,will divide this pri- 100 diameter being connected together for throughtransmis 110 said coilfn portion of said secondary windings being in 125cults for establishing an electrical balance for the repeater saidbalancing means constituting-a part of suidinstrir being divided to formseparate circuits to prevent the distorting currents, the

coil having its secondary windings divided between the divisions ofthemain circuit, and its local windings divided between'the divisions ofthe two local circuits, and

a telephone repeater apparatus directly associated with 5 the said localwindings and inductively associated with the snidinain circuit secondarywindings.

10. in a-telephone repeater stem. the combination of main and localcircuits each divided to form separate circuits, a-coinpound inductioncoil for preventing reactive condary windings of which are divided inservice between the sections of a main tale phone circuit. and the localwindings of which are divided between the sections of the localcircuits. a repeater apparatus associated with the local circuits. saidcoil being 5 the medium for both receiving; and retransmittin all thetelephonic currents between said repeater apparatus and said main line.the repeater apparatus being connected in said local circuits in aconstantly maintained balanced relation whereby it is rendered sensitiveto the 0 received currents and inert to its own currents.

17. in a telephone repeater. a composite repeating induction andretardation coil having a plurality of secondary and local windings fortransforming the telephone cur rents, .ich of said secondary winding-sbeing wound on a separate section of the core and connected in acompound metallic telephone circuit, the several secondary windingsbeing, divided into conductively and inductively connected sections, thesaid sections being arranged to create overlapping magnetic fields andoperative to create a conductive 0 differential condition in the coilfor composite extra currents passing through on each side of thecircuit, a bridging condenser connecting the conductively connectedsections of the coil to form the inductively connected sections for thetelephonic currents which terminate at the coil.

18. in a telephone repeater, the combination of an in ductlon coll o!ring core type, having four secondary wind lugs, each on a separatesection of the core, two of which on either side are connectedconductively but non-inductively together to form noiriiiductiivehalves, -a condenser 0 joining, inductively said conductive halves toform two inductive halves. each oi which is composed of one coil of eachof the conductive halves, and mutually inductive local windingssimilarly disposed on the same core for transformim: in connection withthe secondary windings the 5 repeatertelephonic currents.

in. In a telephone repeater system. a telephone repeater apparatusincluding a local circuit in direct inductive assoiation with the lineconductors of the mainline circuit, a bridge conductor dividing thelocal circuit, a battery and U a transmitter in circuit in the bridgeconductor, and local windings in each side of the local circuit.

20. in a telcphorcrcprutcr apparatus, the combination with a localcircuit. of a bridge conductor in said local cir- (2OIldllCt0i'.'l\second local circuit, and a receiver in said second local circuit,

21. In a telephone repeater system, the combination oi a main linehaving two metallic circuit sections associated with a repeatinginduction coil, a telephone repeater re 0 ceiver-trnnsmitter ilrcircuitwith the local windings of said induction coil and in direct inductiverelation to the secondary windings oisaid coil, and said main linesections being in Circuit with the/secondary windings of said coil, thesecondary wit'idincs being divided and apportioned to 5 said main linesections for respective individual operation therewith, .andauxiliaryconductors provided with inductanccs l' orml p shunts aroundthe repeating coil .for the through transmission of slow-acting currentsand for the protection of the repeater recciver-transmitlcr..

22. in a telephone repeater system. the combination of a main telephonecirc it, the two conductors of which are separately and jointly adaptedfor the transmission of superposed currents. a telephone repeaterstation on said circuit, a bridge connection between the two conductorsof 5 said circuitat' the repeater station, a repeater apparatus at saidstation comprising a receiving: magnet and a variable resistancetransmitter actuated thereby, a composite rcpeuting induction antiretardation coil inductively associntlng said main circuit and saidrepeater apparatus, said coil having a. magnetic core. and primary orlocal and sec cult, a battery and transmitter in circuit in said bridgeondary windings, the secondary winding being divided into four heliceseach helix being wound over a separate section of the magnetic core andconnected in said main telephone circuit so that two helices of the saidsecondary winding will be on each side of said bridge connection; twolocal circuits. one constituting: a tertiary circuit divided by a bridgeconductor containing the receiving magnet, and the other constituting aprimary circuit divided by a bridge conductor containing, thetransmitter and a battery, each of said local circuits containing adivision of said local winding, each division being divided into twogroups, each group having four helices which are connected in pairs oneach side of saidfbridge conductors, each group being wound tocorrespond in position to the helices of said secondary vvindin; eachsection of said magnetic core having three helices, and each sectionconstituting a distinct inductive electromagnetic field; one helix fromeach of said divisions of said local winding forming one of said groupsot'hclices, one helix of which group being on each section of the coreand connected in circuit with said battery, thus one .pair at helices oneach side of the coil is in corresponding position to the two secondaryhelices on each side of said main circuit bridge connection, and thepairs beinr; connected to their local bridge conductor by theirremaining terminals, so that the local circuit containing the batteryand transmitter will be divided by its bridge conductor towel-respond tothe said division and arrange-,

nicnt' oi the secondary circuit ot'ssaid coil, the other group of fourlocal helices being connected in said tertiary circuit and arrangedsimilarly to the first group; 'an auxiliary conductor containing aninductance connected around the said secondary windings to the lineconductors on each side of the main circuit, and conductors containingconde'nscrs connected around said secondary windings tor shuntingtherefrom high frequency through superposed currents.

23. In a telephone repeater system, a, laminated iron ring cororepeating induction coll having four electromagnetic sections,individual secondary and primary mutually inductive windings for eachsection, two divided secondary windlngson each lialf of the core, acrossone diameter, being conductively joined together and having twoterminals for connection to the line, said windings being adapted to hevariously connected, it non-inductance bridge connected on either sideto the inner or joined ends of the two said conductive halves'to formtwo halves inductively connected by a condenseracross asecond diamer terof the ring core at right angles to the first mentioned diameter, saidlatter halves being composed otone coil of each 01' the conductivehalves and both together constituting four overlapping secondarycircuits.

:24. in a telephone repeater system, the combination of a main telephonecircuit, the two conductors of which are separately and jointly adaptedfor the transmission of superposed currents, a telephonic repeaterapparatusassociatcd with said circuit, a repeating induction coil inductivcly connecting said main circuit and said repeater 11pparatus, therepeaterapparatus being connected in ctr-- cult withthe local windingsof said repeating induction coil, the secondary windings of said coilbeing connected in the main vircuit with two windings in each conductorthereof, each two windings being in series relatidh but differentiallyconnected, bridge containing a cotidenscr in terposed between the twomain circuitconductors, and connected to said conductors between the twowindings in each of said conductors, condensers included in each con--ductor of the main circuit, shunting inductance-s connected in circuitaround. the secondary windings of the coil on each side, and condensersconnected around said secondary windings and inductances to shunt fromthe repeater high frequency through superposed currents. I

25. in a telephone repeater system, the combination of a main telephonecircuit, the two conductors of which are jointly and separately adaptedfor the transmission of superposed currents, at telephonic repeatercomprising a receiver and transmitter associated with sald'circuit, a repeatiucinduction coil in the main circuit inductively connecting saidmain circuit and said repeater apparatus, the

- repeater receiver and transmitter both being connected in circuit withthe local windings of said repeating induction coil, and the secondarywindings of said coil being connected in the in: in circuit with twowindings in each conductor thereof, each two windings being in seriesrela tion' but diiferentially connected.

26. lo a telephone repeater system, the combination of a main telephone'cuit, the two conductors oi which are separatl y and ointi v adaptedfor the transmission of superposed currents, a telephonic repeaterapparatus comprising a receiver and transmitter associated with saidcircuit, a repeating induction coil in the main circuit inductivelyconnecting said main circuit and said repeater apparatus. the repeaterrcceiver-trausinitter both being connected in circuit with the localwindings of said re peating induction coil, the secondary windings ofsaid coil being connected in the main circuit with two windings in eachconductor thereof, each two windings being in series relation butdifferentially connected, and a bridge containing a condenserinterposedbetween the two main circuit conductors and connected to saidconductors hetwecn the two windings in each oi said conductors L27. in atelephone repeater & stein, the :ombination of a main telephone circuit.the two conductors of which are separately and jointly adapted for thetransmission of superposed currents, a telephonic repeater apparatus comprising a receiver and transmitter a soeiated with said circuit, arepeating induction coil in the main circuit inductively connecting saidmain circuit and said repeater apparatus, the repeaterreceiver-transinitter both being connected in circuit with the localwindings of said repeating induction coil, the secondary windings oisaid coil being connected in the main circuit with two windings in eachconductor thereof, each two windings being in series relation butdiilerentiailgconnectod, and a bridge conductor olf low resistanceinterposed between the two main circuit: conductors and connected tosaid conductors between the two windings in each of said conductors.

28. in a telephone repeater system, the combination of a main telephonecircuit, the two conductors of which are separately and jointly adaptedfor the transmission of superposed currents. a telephonic repeaterapparatus associated with said circuit. a. repeating induction coilindnctiveiy connecting said main circuit and said repeater apparuins,the repealcr apparatus being connected in circuit with the localwindings at said icpeating induction coil, the secondary windings oisaid coil being connected in the main circuit with two \viudino; in eachconductor thereof, each two windings being in series relation, 2).bridge interposed between the two main circuit conductors and connectedto said conductors between the two windings in each of said conductors,shunting iudueianccs connected in circuit around the secondary windingsot' the coil on each side, and condensers connected around saidsecondary windings and indtu anti-s to shunt from the repeater highfrequency through suporposell currents.

Lll. in a telephone repeater sysle u, the combination of a mam telephonecircuit, the two conductors thereof scpzr ratcljr and jointly adaptedfor the transmission oi superposrd currcnls. a telephonic repeaterapparatus comprising a receiver and lransiuilier associated with saidcircuit a repeating lilrllu'lioii roll in the main (1 uit inductivelycourier-ting said main circuit and said rcpt-atelapparalus. ilurrpeatcrrecoiver-transmitter both being connected in circuit will: the localwindings of s id repeat inc; induction coil, the secondary windings o1id coil a metallic cord-circuit, suitable plugs and jacks for connectingsaid cord-circuit between said main circuits at: Sdid station. aninduction coil the secondary windings of which are in serieseonncriioirin the conductors of the cort'i-circuit; a bridge connectingthe two line conductors of said metallic cord-circuit, a local circuit.a local battery and a repeater appzniatus rompri 'ng' anelectro-Inagnetic receiver and a variable-resisianco transmitter also atsaid station, both the repeater reccirer and transmitter and the localwindings oi saidinduction coil being connected in the local circuits andin direct inductive associatitin with the line conductors of the mainline circuit whereby they are operative to inward inducing currents fromthe main cireuit, but inoperative to the repeating local currents andthe repeated or reproduced currents,

ill. In a telephone repeater stem, a cord circuit having appliances forconnection between main telephone circuits atv a repeater station, aninduction coil having" divided secondary and local windin associatedwith said cord circuit, the secondary wiudiu' s being in seriesconnection in the cord circuit, a bridge connected to the two lineconductors oi? said cord-circuit and between the divided secondarywindings ol rid i1, circuits local to said serially connected secondarywindings, a rcpeator-receiver in one oi aid local circuits and arcpeatertrausuiiltor in another of said local circuits, said localcircuits being in direct inductive association with the line conductorsof, the main line circuit, and a local battery connected in the transluitter local circuit with local windings of said coil, and the repeaterreceiver and transmitter being adapted to responsive repeater action toinducing inward currents from the main telephone circuit. and adapted tobe irrcsponsive or inert to the r01 ting local currents, and to therepeated or reprot'iuccd currents sol up.

32. in a telephone repeater system, the combination of a main linecircuit. a bridge dividing the circuit al a repeater station into twoline circuit sections, a repeater station on said main line circuit,telephones at dis points on said line, circuit, said telephones oriuaiiug currents for reproduction at the repeater station. a re peatcrapparatus coiupriiug an clcclromaguclie telephone receiver and avariable-resistance telephone. tran mitter in repeater relation adaptedto receive the said o Idling currents from one line circuit section andto reproduce for retransmission facsimile currents of increased power tothe associated line rircuit suction and the telephone apparains therein,a repeating iuducliou coil iiuluclircly assocializig the line circuit.scrliops czuzb individually with both the repeater receiver andtransmitter, llusecondary winding ol saidw'oil hating plural windingswhich are apportioned to the line circuit sections for individual andsimultaneous operation. a cord circuit includin lid secondary windings,means associated with llu: rowlcirruil adapted for connecting, disconneting and operating the Hill and repeater receiver and transmitter1':ll'|l \vilh lhe said main line circuit, said ropcator l'llllY andtrans miller cuch lacing in local circuit with primary windings ol thecoil and the transmitter of said ropraliug' induction roll, a battery incircuit with primary windings ol' the coil and tho lrausiuiltcr, andlocal circuit means tor rendering the rcpetiler apparatus operative tothe iuduciug currents from the line circuit sections liul. inoperativeto its repro (lllt'ttl currents said rircuil moans also adapted toseparatithe acti ns in the two circuit sections to prevent reinduccdrem-lion ciiects.

local NATHANIEL (i. \VAlt'llI.

\l'll bosses:

Bum). u l N i imucnn,

